Dale and Betty Bumpers Vaccine Research Center National Institute of Allergy and Infectious Diseases National Institutes of Health Department of Health and Human Services From Antibody to Vaccine a Tale of Structural Biology and Epitope Scaffolds Peter D. Kwong AIDS Vaccine 2009, Paris France 22 October 2009
How to apply structural biology to vaccine development? Understand HIV mechanisms of humoral immune evasion Understand the manner by which the humoral immune system recognizes HIV Utilize structure-assisted vaccine design to develop immunogens that elicit broadly neutralizing antibodies
HIV Viral Spike Has Few Sites of Vulnerability Virus gp41 glycans gp120
Sites of Receptor Binding Must Be Conserved Virus CD4 Host cell Co receptor Broadly reactive b12 antibody competes with CD4 to neutralize HIV-1.
Structure of b12:gp120 Inner domain gp120 outer domain CDR H3 b12 Heavy chain b12 Light chain Zhou et al.
A Site of Vulnerability on HIV-1
BUT, Most CD4BS-Antibodies Are Ineffective 1. Current vaccine regiments can elicit CD4BS antibodies, but these are unable to neutralize primary isolates. 2. Many CD4BS monoclonal antibodies characterized and these are ineffective at neutralization. What mechanisms of evasion shield the initial site of CD4 attachment?
Structure of an Ineffective CD4BS Antibody 1.5e : YU2 core F91 : YU2 core F105 : JRFL F105 : YU2 core F105 : YU2 (core+v3) m14 : YU2 core m18 : YU2 core F105 : JRFL : G3-42 F105 : JRFL : G3-299 F105 : YU2 (core+v3) : G3-42 F105 : YU2 (core+v3) : G3-299 Crystals - - - - X - - - - X - Protein Sources: 1.5 e (J. Robinson) F91 (J. Robinson) F105 (M. Posner) m14, m18 (D. Dimitrov) YU2 core (Wyatt) YU2 core+v3 (Wyatt) JRFL (Sodroski) G3-42 (M. Fung) G3-299 (M. Fung) Lei Chen
Antibody F105 in Complex with a YU2 gp120 Core with Intact V3 Lei Chen Young Do Kwon
Similarity in CD4 and F105 Recognition CD4- binding loop F105-bound CD4-bound D368 R59/100F CD4 F105 Lei Chen Young Do Kwon
CD4- Versus F105-Induced Conformation Unliganded F105-induced CD4-induced Bridging sheet is completely opened up Young Do Kwon
Under the Bridging Sheet Unliganded F105-induced CD4-induced Movement of bridging sheet uncovers otherwise occluded hydrophobic surface. Young Do Kwon
Hydrophobic Immunoprominent Decoy Large hydrophobic glycan-free surface provides an immunoprominent surface to bind antibodies. However, antibodies that bind this surface cannot neutralize. Lei Chen Young Do Kwon
Generality of Decoy Covered F105 binding surface by tethering β20/β21 to inner domain Lei Chen Tongqing Zhou
Generality of Decoy How does b13 bind gp120? Covering F105 binding surface by tethering β20/β21 to inner domain results in loss of binding for most CD4BS antibodies. Only antibodies b12 and b13 were able to bind to Ds109/428 and OD1 constructs (b12 neutralizes, but b13 does not) Lei Chen
b13 Complexed with an HXBc2 gp120 Core Restrained to be in the CD4-Bound State V1/V2 stem gp120 β20/21 b13 Light chain b13 Heavy chain Dennis Burton Ann Hessel Gary Nabel Ling Xu Zhi-Yong Yang Tongqing Zhou
Similarity Between b12 and b13 gp120 CDR H2 CD4-binding loop CDR H3 CDR H2 CDR H3 CDR H1 CDR H1 b12 b13 b13 b12 Tongqing Zhou
V1/V2 of b12 and b13 b12 V1/V2 V1/V2 b13 Young Do Kwon Tongqing Zhou
Modeling Viral Spike Compatibility CD4 (with 17b) F105 EM from Liu et al. Nature 2008 F105- and b13-induced conformations of gp120 are incompatible with the functional viral spikes of most primary HIV-1 isolates. b12 EM from Liu et al Nature 2008 b13 Young Do Kwon Tongqing Zhou
Testing gp140 versus gp120 Binding Viral spike mimic: gp140-cleavage minus-foldon trimer is not a precise mimic of the viral spike, but properties should trend in the same direction Lei Chen
Similarity of Epitopes and Angles of Approach V1/V2 stem gp120 β20/21 F105 Heavy chain F105 Light chain Despite similarity between CD4, F105, b12 and b13, only CD4 and b12 are able to neutralize effectively b12 Heavy chain b13 Heavy chain b12 Light chain b13 Light chain
Precise Targeting Required! The target site is precisely circumscribed by a combination of conformational constraints and N- linked glycosylation. Glycosylation serves to push the immune response toward the bridging sheet. Meanwhile, the surface under the bridging sheet appears to be immunoprominent, and the site of interaction for most CD4BS antibodies. L Chen, Y D Kwon, T Zhou et al. (2009) Science in press.
Understand mechanisms of humoral immune evasion Understand manner by which the humoral immune system recognizes HIV Utilize structure assisted vaccine design to develop immunogens that elicit broadly neutralizing antibodies
Understand mechanisms of humoral immune evasion Understand manner by which the humoral immune system recognizes HIV Utilize structure assisted vaccine design to develop immunogens that elicit broadly neutralizing antibodies
Three Broadly Neutralizing Antibodies Bind to the Membrane Proximal External Region (MPER) of gp41 N-helix C-helix gp41 656 NEQELLELDKWASLWNWFNITNWLWYIK 683 2F5 4E10, Z13 1) 2F5 binds membrane proximal region of gp41 (Katinger). 2) 4E10 binds membrane proximal region of gp41 (Katinger). 3) Z13 binds membrane proximal region of gp41 (Burton).
Antibody 2F5 with gp41 MPER Epitope 2F5 CDRH3 gp41 2F5 654 EKNEQELLELDKWASLW 670 Gilad Ofek 2004 J. Vriol.
Structure of 2F5 Has an Unusual CDR H3 2F5 gp41 2F5 CDRH3 Viral Membrane Does CDR H3 of 2F5 contact membrane?
How to apply structural biology to vaccine development? Understand HIV mechanisms of humoral immune evasion Understand the manner by which the humoral immune system recognizes HIV Utilize structure assisted vaccine design to develop immunogens that elicit broadly neutralizing antibodies
CD4BS Immune Evasion Acknowledgments Dana-Farber M Posner J Sodroski S-H Xiang X Yang NCI D Dimitrov M-Y Zhang NIAID/NIH J Arthos D Van Ryk Scripps D Burton A Hessel M Zwick U Alabama K Davis G Shaw U Washington D Baker W Schief VRC/NIH L Chen B Dey Y Kwon J Mascola G Nabel X Wu R Wyatt L Xu Z-Y Yang T Zhou
VRC/NIH K McKee J Mascola G Nabel G Ofek Y Yang Z-Y Yang Acknowledgments 2F5 CDR H3 Hydrophobicity and Neutralization
CEA Loic Martin Claudio Vita Dana-Farber J Sodroski S-H Xiang X Yang NCI D Dimitrov M-Y Zhang NIAID/NIH J Arthos D Van Ryk Acknowledgments Structure-Assisted Immunogen Design Scripps D Burton A Hessel Ian Wilson M Zwick U Alabama K Davis G Shaw U Washington D Baker W Schief IAVI NAC VRC/NIH B Dey J Guenaga L Kong Y Li J Mascola S Majeed G Nabel G Ofek M Pancera M Tang R Wyatt L Xu Z-Y Yang T Zhou
Structural analysis reveals the sophisticated camouflage of HIV but also the remarkable abilities of the immune system at recognition. Perhaps if the immune system is aided by a structure-assisted vaccine designed (SAVD) immunogen, a broadly neutralizing response against HIV can be elicited. Adi Ofek (l) & Javier Guenaga (r)